Powerful Mars Orbiter Switches to Backup Computer

NASA's Mars Reconnaissance Orbiter passes over the planet's south polar region in this artist's concept illustration. The orbiter's shallow radar experiment, one of six science instruments on board, is designed to probe the internal structure of Mars' polar ice caps, as well as to gather information planet-wide about underground layers of ice, rock and, perhaps, liquid water that might be accessible from the surface. Phobos, one of Mars' two moons, appears in the upper left corner of the illustration. ImageCredit: NASA/JPL/Corby Waste

The
4-year-old Mars Reconnaissance Orbiter is NASA?s youngest spacecraft circling
the red planet and the most powerful to date. Since arriving at the red planet
in 2006, the orbiter has beamed home more data and images than all other Mars
missions combined.

Last week,
the orbiter spontaneously
switched to its Side B backup computer for reasons still unknown to mission
engineers. The computer swap occurred Thursday and sent the Mars Reconnaissance
Orbiter in to a safe mode for protection while it awaited new instructions from
Earth.

Engineers
reactivated the orbiter?s systems on Saturday and restarted its science
instruments two days later.

The $720
million Mars Reconnaissance Orbiter has entered safe mode seven times since it launched toward Mars
in 2005. In two of those instances, one in 2007 and the other in 2008, the
spacecraft switched to its backup computer, mission managers said.

The orbiter?s
latest glitch has some similarities to the two previous computer swaps, they
added.

Earlier
this year, the spacecraft entered safe mode on two occasions after unexpectedly
rebooting its main Side A computer, most likely due to a hit by a stray cosmic
ray or solar particle, mission managers have said. The new malfunction appears
to be unrelated to those events, they added.

The Mars
Reconnaissance Orbiter completed its main mission in 2008 and is currently in
the middle of an extension phase that ends in mid-2010.